In general, a portable electronic device refers to a device that allows the user to access various contents while carrying it, and includes a portable terminal, a Moving Picture Experts Group phase 1 or phase 2 (MPEG-1 or MPEG-2) audio layer 3 (MP3) player, and a personal media player (PMP). The portable electronic device has become multifunctional according to the need of consumers and has gradually become small in size.
In particular, the portable terminals are becoming multifunctional according to various needs of the consumers due to its portability. Further, due to the recent development of technologies, the portable terminals have been used for the multi-convergence of music, movies, televisions (TVs), and games, as well as simple phone functions. A representative apparatus that leads the portable electronic device to multi-convergence is a camera apparatus.
The pixels of the camera apparatus have increased from 300,000 pixels (i.e., video graphic array (VGA) level) to the current high number of pixels, and the camera apparatus has been equipped with various additional functions, such as autofocusing or optical zoom.
Generally, a compact camera module (CCM) is small-sized and is applied to mobile communication devices, such as a camera phone, a personal digital assistant (PDA), and a smartphone, and various information technology (IT) devices, such as a toy camera, and devices on which small-sized camera modules are mounted have recently increased according to various tastes of the consumers.
The camera apparatus employs a semiconductor chip (hereinafter, referred to as an image sensor), such as a charge coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) image sensor (CIS), as a main component, and an image of an object condensed by the image sensor is stored in a memory in the device as data, and the stored data are displayed as an image through a display medium, such as a display panel of the device.
The image sensor is mounted on a board (hereinafter, referred to as a printed circuit board), such as a printed circuit board (PCB) or a ceramic substrate, and a lens cylindrical body including a lens is coupled onto the printed circuit board including the image sensor to assemble the image sensor.
A general structure and assembly process of a camera apparatus is as follows.
The camera apparatus includes a lower module, such as an image sensor module, and an upper module, such as a lens assembly module, which are coupled to each other after being manufactured separately.
First, a process of the lower module of the camera apparatus will be described. The lower module of the camera apparatus may include an image sensor and a printed circuit board. The assembly manner of the image sensor module may include a wire bonding manner and a flip chip bonding manner.
The image sensor module through the wire bonding manner may be configured such that an image sensor is mounted on an upper surface of a printed circuit board through a coupling method, such as die bonding. The image sensor that is mounted on the printed circuit board may form a lower module of the camera apparatus by bonding (hereinafter, referred to as wire bonding) the image sensor to the printed circuit board using an electrical signal line, such as a wire, such that it is electrically connected to the printed circuit board.
The image sensor module, when employing a flip chip technique, may be electrically connected to the bottom surface of the printed circuit board through an electrical connection of a bump and a pad by using a flip chip on which the image sensor is mounted.
Furthermore, a process of the upper module of the camera apparatus will be described. The upper module of the camera apparatus may include a lens assembly, a cover glass or IR filter, and a lens housing including them. A lens assembly including at least one lens module and a correction member that drives the lens module and corrects an image through at least one of automatic driving and manual driving of the lens is mounted on the housing to form the upper module. In particular, the upper module of the camera apparatus may be coupled to the lower module through thermoplastic bonding.
The IR filter may be mounted on the lower side of the housing or the upper side of the image sensor module through an adhesive, such as epoxy.
After the image sensor module is assembled, the optical axis of the image sensor is aligned, and after the upper module is assembled on the lower module, the optical axes of the lens assembly and the image sensor are aligned.
In order to focus the image sensor and the lens, the optical axes of the image sensor and the lens should be located on the same line.
However, the lower module may be mounted while the image sensor is distorted from a surface of the printed circuit board due to distortion of the printed circuit board or an unbalanced surface of the printed circuit board when the image sensor and the printed circuit board is assembled. Accordingly, because the image sensor and the lens module are not located on the same line, the optical axis is distorted.
When the image sensor is distorted, the distortion of the introduced optical axis cannot be corrected, and accordingly, the productivity and quality of the camera apparatus may deteriorate.
Distortion of the optical axis may occur even in the process of assembling the upper module on the lower module. That is, the housing including the lens assembly is seated on and fixed to an upper surface of the printed circuit board on which the image sensor is mounted through thermoplastic bonding, and as described above, the housing seated on and fixed to the surface of the printed circuit board may be mounted while being distorted due to the distortion of the printed circuit board or an unbalanced surface of the printed circuit board.
A defect such as tilting may occur due to a tolerance of a component or lack of precision in the process of assembling the above-mentioned camera apparatus, which directly causes a resolution defect. In detail, a defect may occur in the process of mounting the image sensor on the printed circuit board or in the process of mounting and fixing the housing including the lens assembly to an upper side of the image sensor module, which directly causes the resolution defect.
In particular, because the high-resolution camera apparatus requires a high level as compared with a low-resolution camera apparatus in relation to the alignment of the optical axes of the lens and the sensor, the precision of the device increases and the development and production costs also increase for the high-resolution camera apparatus.
Accordingly, a tilting correction method for a camera apparatus that minimizes tilting of the sensor and the lens and decrease defect rate when the high-resolution camera apparatus is assembled, and facilitates the development of the camera apparatus and reduces production costs, and an apparatus that support the method are required.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.